Interlocking concrete blocks are used for many outdoor construction applications, one of the most common being the construction of retaining walls. Interlocking concrete blocks are thus designed for durability, stability, and aesthetic appeal.
Current methods of manufacturing dry-cast concrete blocks allow the producer to create different face textures and appearances on the block. The common “split-face” appearance is produced for example by forming the concrete blocks and then splitting them after curing to form faces having rough, rock-like appearances. The process is shown in further detail FIGS. 1 through 8, where FIG. 1 is an isometric view of a prior art mold box 10 and draw plate 12 used to form dry cast blocks face to face. FIG. 2 is an isometric view of the prior art mold box 10 and pull draw plate 12 of FIG. 1, with dry mix concrete for blocks 16 having been fed into the mold box 10 from the top. FIG. 3 is an isometric view of the prior art mold box 10 containing dry mix concrete for blocks 16 as in FIG. 2 and to which a press head 18 is applying pressure and vibration thereby to compress the dry mix concrete for blocks 16 and to form the top surface of the blocks 16 (16a, 16b, 16c when separated) being formed. FIG. 4 is an isometric view of the press head 18 of FIG. 3 being withdrawn from the dry mix concrete for blocks 16 after having been applied. FIG. 5 is an isometric view of the draw plate 12 being withdrawn from underneath the compressed dry mix concrete pursuant to the application of the press head 18, revealing keys (grooves) and any chamfers C formed by the presence of the draw plate 12 and individual draw fingers 14. FIG. 6 is an isometric view of the mold box 10 being withdrawn from around the previously-compressed dry mix concrete for blocks 16. FIG. 7 is an isometric view of blades 20a and 20b contacting respective portions of the previously-compressed dry mix concrete for blocks 16 thereby to split the whole into multiple blocks 16a, 16b, and 16c. FIG. 8 is an isometric view of the multiple blocks 16a, 16b, 16c formed by the blades 20a, 20b of FIG. 7 and their “split face” rough and aesthetically-desirable appearance 17a, 17b, and 17c. 
In alternative methods, such blocks are formed on their sides, or a specially-designed texture, such as a natural stone-like texture, can be “pressed” into the face of the blocks during the dry-cast process.
To provide vertical interlock between blocks, some type of shear key is formed into blocks, such as a respective tongue (top) and groove (bottom) or a rear lip, a lug, etc. Such a key/groove pair is shown in FIG. 8. The key/groove pair provides vertical shear resistance between the blocks as well as an aid in alignment of blocks with each other. Some alternative methods for achieving vertical interlock between successive courses involve using auxiliary plastic or fiberglass pins, clips, or connectors, added during construction of the wall. However, such auxiliary elements require an extra installation step, their application is subject to human error, and they increase costs.
Current design trends in architecture and landscape architecture are emphasizing clean, linear lines and smooth surfaces. Use of shadow and light to create a visually appealing fascia on buildings and walls is becoming a primary tool of many architectural designers. However, known blocks and methods of installation do not easily enable a builder to achieve the new modern appearance we desired in a retaining wall having protrusions producing highlights and shadows.